1. Field of the Invention
This invention relates to a communication terminal device having a facsimile communicating function and a reception controlling method for a communication terminal device.
2. Description of Related Art
Currently, IP (Internet Protocol) networks are widely used and calling number display services are offered. In some cases, in order to perform facsimile communications, a communication terminal device having a facsimile function is connected to a terminal adapter (TA) to establish connection with an IP line, and is subscribed to the calling number display service.
Japanese Patent Application Publication No. 2004-289212 discloses a facsimile device configured to perform facsimile communications using a modem that conforms to the communication mode of the network to which it is connected and by considering delays at the same time.
Referring to FIGS. 4 to 7, description is provided for conventional operation of a receiver having a facsimile function and configured to perform facsimile communication connected to an IP line and subscribed to the calling number display service.
FIG. 4 is an operation time chart for a first related art receiver. The response time of an unillustrated receiver, i.e., the time for which the receiver waits to recognize an incoming call after the arrival of a first ring signal, may be set to any one of one ring after 5 seconds, after 10 seconds, after 15 seconds, and after 20 seconds. Moreover, in this example, the minimum value of ring signal ON time, i.e., the minimum length of time during which the ring signal needs to be ON to be determined an effective ring signal, is set to 650 ms. The modem function may be either V. 34 or V. 17.
When a facsimile communication call comes from an unillustrated transmitter at the other end of the communication (hereinafter simply called a counterpart), a ring signal (401) comes from an exchange to the receiver. Since the minimum value of the ring signal ON time is set to 650 ms, the ring signal (401) having the ON time for 0.5 seconds is determined not-effective.
Even if the response time is set to “one ring,” the receiver determines that an information reception terminal start signal (401), which is the ring signal, is not an incoming call. Accordingly, the exchange neither operates in a number display sequence nor sends out a MODEM signal to indicate inclusion of the telephone number of the transmitter (411). Determining not to operate the number display signal sequence, the exchange sends out a subsequent ring signal (412) after a certain time period. This signal has an ON time of 0.25 to 0.3 seconds. Accordingly, this signal is not determined effective according to the minimum value of the ring signal ON time, which is set to 650 ms. Therefore, the receiver cannot receive a call and proceed with communication (413) even when the response time reaches a time-out.
FIG. 5 is an operation time chart for a second related art receiver. A setting of response time of an unillustrated receiver is determined as “one ring.” Moreover, the minimum value of the ring signal ON time is set to 200 ms (510). The modem function may be either V. 34 or V. 17.
When a facsimile communication call comes from an unillustrated counterpart communication terminal, a ring signal (501) comes from an exchange to the receiver. Since the minimum value of the ring signal ON time is 200 ms, the ring signal (501) having the ON time of 0.4 to 0.6 seconds is determined effective.
Moreover, since the response time is set to “one ring,” the receiver connects to a line (512) upon arrival of the first ring signal (501). As the receiver determines that an information reception terminal start signal (501) which is the ring signal (501) is an incoming call, the exchange operates in the number display sequence and sends out a MODEM signal including a telephone number of the transmitter (513). To perform facsimile reception, the receiver sends out an ANSam signal (an amplitude-modulated answer tone) signal when the modem function is V. 34, or sends out a CED signal (a single tone at 2100 Hz) when the modem function is V. 17. However, since the exchange is operating in the number display sequence, the exchange blocks the signal transmitted from the receiver, and consequently the receiver fails to establish communication (514).
FIG. 6 is an operation time chart for a third related art receiver. A response time of the receiver may be set as any one of 10 seconds, 15 seconds, and 20 seconds. Here, the response time is set to 10 seconds (610). The minimum value of a ring signal ON time is set to 650 ms. The modem function may be either V. 34 or V. 17.
When a facsimile communication call comes from an unillustrated counterpart communication terminal, a ring signal (601) comes from an exchange to the receiver. Since the minimum value of the ring signal ON time is 650 ms, the ring signal (601) having the ON time of 0.5 seconds is determined not-effective.
The receiver does not determine that an information reception terminal start signal (601), which is the ring signal (601), is an incoming call. Accordingly, the exchange neither operates in the number display sequence, nor sends out a MODEM signal that indicates inclusion of a telephone number of the transmitter (612). Determining not to operate the number display signal sequence, the exchange sends out a next ring signal (613) after a certain time period. This signal has the ON time of 0.25 to 0.3 seconds. Accordingly, this signal is determined not-effective according to the minimum value of the ON time which is 650 ms. Therefore, the receiver cannot recognize the incoming call at a time-out of the response time (614) and fails to proceed with communications (615).
FIG. 7 is an operation time chart for a fourth related art receiver. The response time of the receiver may be set to any one of 10 seconds, 15 seconds, and 20 seconds. Here, the response time is set to 10 seconds (710). The minimum value of a ring signal ON time is set to 200 ms (711). The modem function is assumed to be V. 34.
When a facsimile communication call comes from an unillustrated counterpart communication terminal, a ring signal (701) comes from an exchange to the receiver. Since the minimum value of the ring signal ON time is 200 ms, the ring signal (701) having the ON time of 0.4 to 0.6 seconds is determined effective.
However, since the response time is “10 seconds,” the receiver does not determine that an information reception terminal start signal (701), which is the ring signal (701), is an incoming call. Accordingly, the exchange neither operates in the number display sequence nor sends out a MODEM signal that indicates inclusion of a telephone number of the transmitter (713). The exchange determines that the signal does not represent the number display sequence and sends out a next ring signal (714) after a certain time period. This signal has the ON time of 0.25 to 0.3 seconds and is therefore determined effective according to the minimum value of the ON time which is 200 ms. The receiver connects to line (716) at a time-out of the response time (715). However, when connection to the IP line is established, a communication error may occur (716).
As described above, the first to fourth related art examples have the following problems: a failure to establish communication may occur due to, for example, the influence of a delay or discard of a packet on the IP line; a failure to establish communication may also occur because the exchange which is operating in the number display sequence blocks the signal sent from the receiver to the transmitter; and the receiver cannot recognize an incoming call because a ring signal sent from a TA (terminal adaptor) is ambiguous.